Out of Gauge Cargo by Road: Limits, Permits and Trailers

Out of gauge cargo is any load that makes the vehicle exceed the standard legal length, width, height or weight for the road. In the EU those standard limits come from Directive 96/53/EC, and going beyond them needs a special permit, often with escorts, a set route and extra marking.

The rules for abnormal transport are national. The EU sets the standard maxima for international traffic, but each country decides how permits, escorts and markings work on its roads. This guide explains the common principles and gives examples, so check the rules of every country on the route before you quote or load.

The standard EU limits

Directive 96/53/EC, Annex I, sets the maximum dimensions that vehicles in international traffic between member states must be allowed. Anything within them is a normal load. Anything beyond them is out of gauge.

The 4 m height is the one that varies most. Several countries allow higher vehicles nationally, and the UK and Ireland have different rules again. A load that is legal at 4.20 m at home may need a permit as soon as it crosses a border.

For axle loads, see EU truck axle weight limits. Typical maxima are 10 t on a single non-driving axle, 11.5 t on a single driving axle and 24 t on a tridem with normal spacing. For trailer sizes inside the standard limits, see semi-trailer dimensions.

Indivisible loads

Permits for abnormal transport are generally given only for indivisible loads. Directive 96/53/EC defines one as a load that cannot be split into two or more loads for road transport without undue expense or risk of damage, and that, because of its size or mass, cannot be carried by a vehicle within the standard limits.

• Indivisible: a transformer, a bridge beam, a boat hull, a 3.2 m wide machine frame, a wind turbine blade.
• Divisible: steel beams that can be split over two trucks, a machine that can be taken apart with normal tools, or extra pallets added to a permitted load to fill space.

Authorities can refuse a permit if the load could reasonably be split, and adding other goods to an abnormal load is usually not allowed.

Permits

Each country issues its own permits, sometimes through a national body and sometimes through regional road authorities. The common pattern is similar:

1. 1Describe the load and vehicle. Dimensions, total weight, axle loads, axle spacing and the type of trailer.
2. 2Propose a route. The authority checks bridges, tunnels, roundabouts and roadworks, and may change it.
3. 3Wait for the permit. Lead times range from a few days for simple single-trip permits to several weeks for very large or heavy moves. Some countries offer long-term permits for repeated moves within set limits.
4. 4Follow the conditions. Permits set the route, time windows (often night or outside rush hours, and not on weekends or holidays), maximum speed, escort needs and marking.

In the UK, for example, many moves are notified rather than permitted. Under the Road Vehicles (Authorisation of Special Types) (General) Order 2003 and the Construction and Use Regulations, police and road and bridge authorities must be told in advance, with the notice period and the need for a special order rising with size and weight. Germany, by contrast, requires a permit under the road traffic rules for most oversize moves. These are examples only; the thresholds change between countries.

Escorts

Escort vehicles warn other road users and help the truck through junctions and narrow sections. Whether you need one, and what kind, depends on the width, length, height and weight, and on the country.

• Private escort vehicles are the most common, often with a sign board and lights. Several countries license escort drivers and set rules for their vehicles.
• Police escorts are required in some countries for the largest moves, or to stop traffic at junctions.
• Attendants on the vehicle itself may be required for long overhangs or wide loads, for example in the UK.

As a rough rule, many countries start to ask for an escort somewhere above about 3 m width or 25 to 30 m length. Treat those numbers as a guide only. The permit is what decides.

Overhang and marking

Long items such as pipes, beams and timber often stick out at the back of the vehicle. Overhang rules apply even when the vehicle is not abnormal, and they vary between countries. Two examples:

Spain and Italy require a square warning panel with red and white diagonal stripes on loads that project at the rear. Other countries use flags, panels or lights. If a load crosses several countries, it must meet the marking rules of each one, which in practice often means carrying more than one type of marker.

Wide loads need marker boards, extra lights and often warning signs and amber beacons. The permit usually lists what is needed.

Choosing the trailer

The trailer decides how much height you have under the 4 m line, and how long and heavy the load can be. The deck heights below are typical and vary by maker and tyre size.

1. 1A machine 3.45 m tall, 2.40 m wide, 14 t. On a flatbed with a 1.30 m deck, the total height is 4.75 m, well over 4 m. On a step deck at 0.90 m it is 4.35 m, still over. On a low loader with a 0.45 m well it is 3.90 m, within the standard height. The width is within 2.55 m, so this may be a normal load if the weight and axles also stay within limits.
2. 2A steel beam 22 m long, 9 t. A standard semitrailer deck is about 13.6 m, so the beam would overhang by over 8 m. An extendable flatbed opened to about 20 m leaves a rear overhang of about 2 m. The vehicle is now over the 16.50 m length limit, so it needs a permit in most countries, but the overhang is short enough to mark and secure safely.

Axle loads and centre of gravity

Out of gauge loads are often concentrated: a 30 t transformer sits on a few square metres of deck. The position along the trailer decides how much each axle group carries. Too far forward and the tractor's drive axle or the kingpin is overloaded; too far back and the trailer axles are. Permits usually state maximum axle loads, and some roads and bridges have lower limits.

• Place the centre of gravity of the load where the trailer maker says. Many low loaders have a load distribution diagram that shows the allowed weight at each point of the deck.
• Check the centre of gravity height. A tall, heavy machine on a low loader is stable; the same machine on a flatbed is higher and more likely to tip in bends and crosswinds.
• Keep the load centred across the width. An off-centre heavy load loads one side of the axles more and makes the vehicle lean.
• Secure for the forces, not the weight alone. EN 12195-1 applies, and heavy machines need chains, blocking and often mats. See load securing basics.

For the method of finding a load's centre of gravity, see centre of gravity of a load.

Route surveys

For anything beyond a simple wide load, the route must be checked before the move. The authority checks structures, but the carrier checks whether the vehicle can physically get through.

• Height: bridges, gantries, overhead cables, traffic lights, trees. Allow for the load moving up and down on bumps.
• Width: narrow roads, bridges with parapets, parked cars, road signs and traffic islands.
• Turning: roundabouts and junctions, especially for long extendable trailers. A swept path drawing helps.
• Weight: bridge limits, weak culverts, soft verges and site access roads.
• Sites: space to unload at the destination, ground strength for cranes, and access for escorts.

For very large moves, specialist surveyors measure clearances and model the swept path.

Checklist for an out of gauge move

1. 1Measure the load, its lifting points and centre of gravity, and confirm it is indivisible.
2. 2Choose the trailer that keeps the load as low and as short as possible.
3. 3Calculate the axle loads and check them against the trailer and the road limits.
4. 4Apply for permits in every country on the route, allowing enough lead time.
5. 5Book escorts, plan the marking for each country, and survey the route.
6. 6Secure the load to EN 12195-1, and check it after the first few kilometres.

Plan the normal part of the load too

Many projects mix one or two out of gauge items with a lot of normal cargo: spare parts, cable drums, crates. Planning that part well can stop a second permit being needed. See machinery transport and the manufacturing use case, and use the vehicle settings manual to set up an open trailer with your own deck size.